Flowering time in photoperiodic flowering plants is a key developmental switch that is affected by environmental signals perceived by the leaves. An important component of the signalling pathway that regulates flowering is the Flowering Locus T (FT) gene. When a plant is induced to flower a phloem-mobile signal termed “florigen” is produced which is transported through the phloem translocation stream to the shoot apical meristem (SAM) where it induces floral development1,2. In Arabidopsis, the mobile florigen has been shown to be encoded by the Flowering Locus T (FT) gene. FT transcribes mRNA specifically in phloem cells but not in the SAM3. Its protein product, however, functions at the shoot apex4-6. Arabidopsis FT is a small globular 23 kd protein consisting of 175-amino acids (aa) with homology to the mammalian phosphatidylethanolamine binding protein (PEBP) or Raf kinase inhibitor protein. FT belongs to a group of six closely related proteins, which includes TFL1 and CENTRORADIALIS (CEN) of Antirrhinum. 
There is collective evidence that the Arabidopsis FT protein7,8 and its tomato SFT9, rice Hd3a10 and Cucurbit Cm-FTL½11 orthologs act as a component of the non cell-autonomous flowering signal that is transported through the phloem into the SAM, whilst the role of FT mRNA movement in long-distance florigenic signalling remains unknown12. Once FT is present in the SAM, it interacts with a bZIP transcription factor, FD, encoded by Flowering Locus D to activate floral identity genes such as APETELA 1 and SUPPRESSOR OF OVEREXPRESSION OF CO1. The latter activates LEAFY and induces flowering4,6. Natural genetic variation in genes controlling the expression of the rice FT ortholog Hd3a, and in Hd3a itself, contribute to diversity of flowering time in cultivated rice13. Overexpression of FT in transgenic plants from several species is associated with early flowering. U.S. Pat. No. 6,225,530 describes an isolated polynucleotide encoding an FT polypeptide. Hanzawa et al also describes modified FT and their expression sequence in plants14.
Flowering time and quantity of flowers (and seed) are crucial aspects of crop yield and quality and there is a need in agriculture to create new tools to control the time and amount of flowering and seed production in a wide variety of plant species. As well as enhancing plant productivity by increasing flowering, in certain plant species it is desirable to delay or prevent flowering altogether. The present invention is aimed at addressing these needs. Bioengineering of FT or creating novel FT alleles by TILLING, mutation breeding and selection of FT may provide useful alleles for breeding of novel crops to enhance productivity to meet rapid increase of global demand for food, feed and fuel.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.